1. Field of the Invention
The present invention relates to a gate of a die and mold, and a die and mold for injection molding. More particularly, the present invention relates to a gate of a die and mold for manufacturing a mold product, a die and mold for manufacturing a light-guide plate used for a backlight unit through injection molding, and a method of manufacturing the same.
2. Description of the Related Art
A liquid crystal display (“LCD”) apparatus is a type of flat display apparatus that has recently been in the spotlight, and is lightweight and slim rendering it useful in various fields such as mobile phones, monitors, televisions, etc.
The LCD apparatus is a light-receiving type display apparatus that displays an image using light that is externally provided to the LCD apparatus. Therefore, the LCD apparatus requires an additional backlight unit that provides the light to the LCD apparatus.
The backlight unit, in general, includes a light source, a light-guide plate diffusing the light from the light source, optical sheets diffusing or condensing the light exiting from the light-guide plate, and a reflective sheet.
The backlight unit may be classified as either a direct-illumination type or an edge-illumination type. In the direct-illumination type, the light source is disposed under the light-guide plate and emits the light to an upper direction, and the light-guide plate receives the light from the light source disposed under the light-guide plate and diffuses the light to the upper direction. In the edge-illumination type, the light source is disposed at a side portion of the light-guide plate, and the light incident from the light source passes through the light-guide plate and diffuses to an LCD panel that is disposed over the light-guide plate.
Injection molding is a method often used for manufacturing light-guide plates. Generally, the injection molding process uses a thermoplastic resin that is injected into a die and mold through an injection portion of the die and mold for the light-guide plate. Prior to injection, the thermoplastic resin is melted down and additives, such as a pigment, a resin stabilizer, a plasticizer, a filler, etc. may be included. The thermoplastic resin is filled into a cavity formed in the die and mold which forms a shape of the light-guide plate corresponding to the design of the mold. In particular, the thermoplastic resin is injected through a gate of the die and mold, which is cut and finished once the thermoplastic resin has hardened.
However, the injection molding manufacturing process causes deformation of the light guide plate due to residual stress, which in turn puts pressure on elements of the LCD device incorporating the deformed light-guide plate that are adjacent to the light-guide plate. As a result, pooling defects, white spot defects, etc., resulting from the residual stress may occur with respect to the LCD panel.